1. Field of the Invention
The disclosure generally relates to an antenna structure, and more particularly, to a directional antenna structure with a dipole antenna element.
2. Description of the Related Art
With the progress of mobile communication technology, portable electronic devices, such as portable computers, mobile phones, tablet computers, multimedia players, and other hybrid functional mobile devices, have become more common. To satisfy user demand, portable electronic devices can usually perform wireless communication functions. Some functions cover a large wireless communication area, for example, mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some functions cover a small wireless communication area, for example, mobile phones using Wi-Fi, Bluetooth, and WiMAX (Worldwide Interoperability for Microwave Access) systems and using frequency bands of 2.4 GHz, 3.5 GHz, 5.2 GHz, and 5.8 GHz.
Since the interior space of a mobile device is limited, its antenna structure for wireless communication should have as small a size as possible. A conventional high directional antenna structure is often limited by a long distance from a radiation element to the reflection plane thereof, and cannot be applied to a variety of small mobile devices.